Optimized temperature and deadspace correction improve analysis of multiple breath washout measurements by ultrasonic flowmeter in infants
Optimized temperature and deadspace correction improve analysis of multiple breath washout measurements by ultrasonic flowmeter in infants
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DOI：
10.1002/ppul.20674
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发表时间：
2007-10-01
影响因子：
3.1
通讯作者：
Frey, U.
中科院分区：
文献类型：
--
作者：
Latzin, P.;Sauteur, L.;Frey, U.
背景：使用超声波流量计和多次呼吸冲洗（MBW）评估肺容量（FRC）和通气不均匀性已被用来提供有关婴儿肺部疾病的重要信息。针对温度和外部死腔对主流摩尔质量 (MM) 信号进行次优调整可能会导致呼吸期间潮气量变化极小的婴儿出现分析错误。方法：我们测量了 5 周龄人类婴儿的呼气温度，并通过计算机模拟模型检查了温度和死腔变化对 FRC 结果的影响。然后导出了一种具有优化温度和死空间设置的新分析方法，测试了分析误差的稳健性，并与以前使用的分析方法进行了比较。结果：面罩内的温度比之前假设的更高，死腔体积的变化也更大。当使用先前使用的分析模型获得时，两者都对 FRC 和 LCI 结果显示出相当大的影响，并且具有高变异性。使用测量的温度，我们优化了模型参数并测试了新得出的分析方法，发现该方法对死空间的变化更加稳健。两种分析方法之间的比较显示出系统差异和广泛的分散性。结论：修正的死空间和更现实的温度假设提高了婴儿超声波流量计获得的 MM 测量值分析的稳定性。这种新的分析方法使用目前唯一可用的婴儿商用超声波流量计，可能有助于提高分析的稳定性，并进一步促进婴儿肺容量和通气不均匀性的评估。
Background: Assessment of lung volume (FRC) and ventilation inhomogeneities with ultrasonic flowmeter and multiple breath washout (MBW) has been used to provide important information about lung disease in infants. Sub-optimal adjustment of the mainstream molar mass (MM) signal for temperature and external deadspace may lead to analysis errors in infants with critically small tidal volume changes during breathing. Methods: We measured expiratory temperature in human infants at 5 weeks of age and examined the influence of temperature and deadspace changes on FRC results with computer simulation modeling. A new analysis method with optimized temperature and deadspace settings was then derived, tested for robustness to analysis errors and compared with the previously used analysis methods. Results: Temperature in the facemask was higher and variations of deadspace volumes larger than previously assumed. Both showed considerable impact upon FRC and LCI results with high variability when obtained with the previously used analysis model. Using the measured temperature we optimized model parameters and tested a newly derived analysis method, which was found to be more robust to variations in deadspace. Comparison between both analysis methods showed systematic differences and a wide scatter. Conclusion: Corrected deadspace and more realistic temperature assumptions improved the stability of the analysis of MM measurements obtained by ultrasonic flowmeter in infants. This new analysis method using the only currently available commercial ultrasonic flowmeter in infants may help to improve stability of the analysis and further facilitate assessment of lung volume and ventilation inhomogeneities in infants.